BACKGROUND: Acute occlusion of left circumflex (LCx) or obtuse marginal (OM) arteries can present as ST elevation myocardial infarction (STEMI) or non-ST elevation myocardial infarction (NSTEMI). NSTEMI patients (pts) with occlusions have worse outcomes than those without occlusions, but no studies specifically examine outcomes in acute myocardial infarction (AMI) pts with LCx/OM occlusion. This study aims to define the incidence of NSTEMI in pts presenting with LCx/OM occlusion and analyzes clinical characteristics and outcomes in those presenting with NSTEMI compared to STEMI.METHODS AND MATERIALS: A review of our catheterization and STEMI database was performed to identify AMI pts presenting with LCx or OM occlusion from 1/1/2007 to 7/31/2009 at the Medical College of Virginia. Patients were divided into STEMI and NSTEMI groups, and a chart review was performed. Primary end-points were in-hospital mortality (HM), cardiogenic shock (CS), and in-hospital CHF. Secondary end-points included peak CK-MB and time to catheterization, as well as combined end-points of 1-month mortality, and recurrent AMI and CHF.RESULTS: Fifty-six pts met inclusion criteria, 54% of whom presented with NSTEMI. STEMI pts were significantly more likely to meet the primary end-points, as well as the combined secondary end-points. They had shorter times to catheterization but larger infarct sizes. Patients with left or mixed coronary dominance were more likely to have STEMI.CONCLUSIONS: AMI pts with LCx/OM occlusion present with NSTEMI as often as STEMI. Those with NSTEMI have better outcomes, which may be related to right coronary dominance.SUMMARY: Patients with acute LCx or OM occlusion present with NSTEMI as often as STEMI, but those with STEMI have worse outcomes. The difference in presentation may be related to coronary dominance.